1. Field of the Invention
The present invention relates to cellular communication systems. Particularly, the present invention relates to systems and methods for implementing an interleaver in a digital cellular communication system.
2. Description of the Related Art
Cellular communications have exploded worldwide in recent years. In undeveloped areas, it has proven a cost effective means of compensating for a lack of infrastructure, providing ready communication links years ahead of any possible deployment of land line systems. In developed areas, cellular systems offer convenience and new features that have quickly grown to become an indispensable adjunct to the existing phone system. As cellular has become ubiquitous, standards have naturally developed in order to reduce the need for duplicate hardware.
The global system for mobile communications (GSM) is a digital cellular communications standard which was initially developed in Europe and has gained rapid acceptance and market share worldwide. It was originally designed to be compatible with the integrated services digital network (ISDN) standard. Thus, the services provided by GSM are a subset of the standard ISDN services, speech being the most basic. A broader range of criteria in the development of GSM include spectrum efficiency, international roaming, low cost mobile and base stations, voice quality and the ability to support new services. Over time, the GSM standard has broadened and evolved to include a variety of channel and coding formats.
Fundamentally, the GSM standard calls for interleaving, a process of transmission bit reordering to make the transmission more robust; interference effects and other harmful influences are diminished overall in the received transmission. However, performing the interleaving process can be memory intensive, requiring storage of large tables that guide bit reordering. This places a burden on transmission and reception.
There is a need for efficient methods and apparatuses for performing interleaving, particularly for the GSM standard. As detailed hereafter, these and other advantages are obtained with the present invention.